peripheral nervous systemn. The part of the vertebrate nervous system constituting the nerves outside the central nervous system and including the cranial nerves, the spinal nerves, and the sympathetic and parasympathetic nervous systems.

peripheral nervous systemThe part of the nervous system in vertebrate animals that lies outside of the brain and spinal cord (central nervous system). It includes the nerves that extend to the limbs and many sense organs. Compare central nervous system.